Synthesized spectral line profiles along the pink arrow shown in Fig. 6a at t = 269 s by using the RH1.5 code. The Hα spectral line profile (pink solid line) and the background profile (pink dot-dashed line) are shown in (a), the Hα spectral line profile found by subtracting the background line profile (pink dashed line) is shown in (b), and the Si IV spectral line profile (pink solid line) is shown in (c).